[PATCH] arm: crypto: add a check for crypto extensions support.

[chalianis1@gmail.com]

From: Chali Anis <chalianis1@gmail.com>

In some configuration the CPU may raise an exception bacause of an
unknown instruction if it does not support Crypto Extensions for
example in some BCM281X (RPi3B in my case) when running barebox
as an EFI Payload, where the EFI stops with a synchronous execption
See bellow:
Synchronous Exception at 0x0000000037BFF548
SP 0x0000000037F798C0 ELR 0x0000000037BFF548
SPSR 0x20000209 FPSR 0x00000000
ESR 0x02000000 FAR 0x14F64325185430BF
ESR : EC 0x00 IL 0x1 ISS 0x00000000

Signed-off-by: Chali Anis <chalianis1@gmail.com>
---
 arch/arm/crypto/sha1-ce-glue.c | 7 +++++++
 arch/arm/crypto/sha2-ce-glue.c | 9 +++++++--
 arch/arm/include/asm/sysreg.h  | 6 ++++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/arch/arm/crypto/sha1-ce-glue.c b/arch/arm/crypto/sha1-ce-glue.c
index 5b49237573fa..fea15f295a00 100644
--- a/arch/arm/crypto/sha1-ce-glue.c
+++ b/arch/arm/crypto/sha1-ce-glue.c
@@ -14,6 +14,7 @@
 #include <linux/linkage.h>
 #include <asm/byteorder.h>
 #include <asm/neon.h>
+#include <asm/sysreg.h>
 
 MODULE_DESCRIPTION("SHA1 secure hash using ARMv8 Crypto Extensions");
 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
@@ -88,6 +89,12 @@ static struct digest_algo m = {
 
 static int sha1_ce_mod_init(void)
 {
+	uint64_t isar0;
+
+	isar0 = read_sysreg(ID_AA64ISAR0_EL1);
+	if (!(isar0 & ID_AA64ISAR0_EL1_SHA1_MASK))
+		return -EOPNOTSUPP;
+
 	return digest_algo_register(&m);
 }
 coredevice_initcall(sha1_ce_mod_init);
diff --git a/arch/arm/crypto/sha2-ce-glue.c b/arch/arm/crypto/sha2-ce-glue.c
index 88cbc7993dac..8479b3c60cb3 100644
--- a/arch/arm/crypto/sha2-ce-glue.c
+++ b/arch/arm/crypto/sha2-ce-glue.c
@@ -14,8 +14,7 @@
 #include <linux/linkage.h>
 #include <asm/byteorder.h>
 #include <asm/neon.h>
-
-#include <asm/neon.h>
+#include <asm/sysreg.h>
 
 MODULE_DESCRIPTION("SHA-224/SHA-256 secure hash using ARMv8 Crypto Extensions");
 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
@@ -116,6 +115,12 @@ static struct digest_algo sha256 = {
 
 static int sha256_ce_digest_register(void)
 {
+	uint64_t isar0;
+
+	isar0 = read_sysreg(ID_AA64ISAR0_EL1);
+	if (!(isar0 & ID_AA64ISAR0_EL1_SHA2_MASK))
+		return -EOPNOTSUPP;
+
 	return digest_algo_register(&sha256);
 }
 coredevice_initcall(sha256_ce_digest_register);
diff --git a/arch/arm/include/asm/sysreg.h b/arch/arm/include/asm/sysreg.h
index 7d567e08d8b7..6f47016e54e8 100644
--- a/arch/arm/include/asm/sysreg.h
+++ b/arch/arm/include/asm/sysreg.h
@@ -12,6 +12,12 @@
 #include <asm/system.h>
 #include <linux/stringify.h>
 
+/*
+ *	ARM64 registers
+ */
+#define ID_AA64ISAR0_EL1_SHA1_MASK      0xF00UL
+#define ID_AA64ISAR0_EL1_SHA2_MASK      0xF000UL
+
 /*
  * Unlike read_cpuid, calls to read_sysreg are never expected to be
  * optimized away or replaced with synthetic values.
-- 
2.34.1